The present invention relates to fluid line couplings and, more particularly, to quick-connect tubular couplings.
In U.S. Pat. No. 4,055,359, a quick-connect tubular coupling is disclosed comprising a pair of tubular elements which, when properly assembled with one another, form a fluid-tight coupling. The first tubular element is provided with an externally mounted cage which houses a garter spring. The end of the second tubular element is flared and sized to be received in the cage. The two tubular elements are assembled by pushing the second tubular element over the first tubular element so that the flared end of the second tubular element enters the cage and forces the garter spring to expand and pass over same. After passing over the flared end, the garter spring is interposed between the cage and the flared end for securing the first and second tubular elements in assembly.
Fluid is prevented from passing from the coupling by a pair of O-rings retained on the first tubular element. The O-rings are positioned at spaced-apart locations along the outer surface of the first tubular element and engage with the inner surface of the second tubular element during assembly. The O-rings are sized so that they are compressed between the two tubular elements after assembly to produce the requisite seal.
Because of their size, the O-rings create frictional resistance to the assembly of the two tubular elements with the resistance increasing when both O-rings are compressed. The resulting frictional resistance has sometimes resulted in an operator mistakenly believing that the coupling has been properly connected when, in fact, it has not. If proper connection is not made, the first and second tubular elements will eventually separate during normal operation resulting in loss of fluid from the system.
Assembly of the first and second tubular elements is further hindered by the substantial force required to expand the garter spring so that it can pass over the flared end of the second tubular element. If the coupling is located in a difficult to reach location of an engine compartment, the substantial force required to expand the garter spring can be especially problematic.
A further problem occurs when the garter spring becomes trapped between the cage and the flared end of the second tubular element. When this occurs, the garter spring is prevented from passing over the flared end of the second tubular element. This may result when the garter spring is not properly centered about the first tubular element prior to assembly.
Accordingly, there is a need for an improved tubular coupling which can be easily assembled by an operator with little risk that an improper connection will be made.